1. Field of the Invention
The present invention relates generally to band tightening devices, and more particularly is a plastic band tightening device with an improved cutting mechanism.
2. Description of the Prior Art
The prior art includes several devices that utilize known methods of cutting a strapping band. Some references representative of the prior art are disclosed in U.S. Pat. No. 4,644,646 to Eli M. Ladin; U.S. Pat. No. 6,047,742 to Barlasov; U.S. Pat. No. 6,962,108 to Hsiu-Man Yu Chen; and U.S. Pat. No. 7,100,499 to Hsiu-Man Yu Chen.
These prior art devices teach a design such as that shown in FIG. 1. The device in FIG. 1 includes a frame 1′, a cutting mechanism 2′, a tightening mechanism 3′, and a band holding mechanism 4′. The cutting mechanism 2′ comprises a stationary cutter 21′, a pivoting cutter 22′ mounted inside the stationary cutter 21′, and an actuating lever 23′ mounted on the pivoting cutter 22′.
To begin a banding cycle, the operator pushes down on a handle 31′, which raises the gripper 41′ and allows the user to insert the first end 61′ of a band 6′ between the gripper 41′ and the frame 1′. When the user releases the handle 31′, the gripper 41′ holds the first end 61′ of the band 6′ in place.
During the tightening operation, the second end 62′ of the band 6′ is threaded trough the cutting mechanism 2′ and a windlass 32′ of a tightening mechanism 3′. The operator applies force to the handle 31′ and tightens the band 6′. When sufficient pulling force has been applied, and the two ends 61′, 62′ of the band are secured with the seal 5′, the operator presses the handle 31′ down a second time to trigger the actuating lever 23′ so that the pivoting cutter 22′ cuts the second end 62′ of the band 6′.
A significant drawback in the prior art design is that the two cutting edges 21′, 22′ of the cutting mechanism 2′ interact two times during each operational cycle. The first time the two cutting edges 21′, 22′ contact each other is when the operator pushes the handle 31′ down to raise the gripper 41′ to load the first end 61′ of the band 6′. The second end 62′ of the band 6′ is not inserted in the cutting mechanism 2′ during loading. The second interaction of the two cutting edges 21′, 22′ is at the end of the operating cycle when the operator pushes the handle 31′ down to cut the second end 62′ of the band 6′ which has been wound around windlass 41′ during the tightening operation. The twice per cycle contacts of the stationary cutter 21′ and the pivoting cutter 22′ greatly accelerates the deterioration of the working edges of the cutter 21′, 22′. The edges wear out quickly, and soon do not cut the band 6′ efficiently. This is especially true when the device is used on cord straps with a thin fiber structure.
Accordingly, it is a chief object of the present invention to provide a banding device in which the number of contacts of the cutting edges of the cutting mechanism is reduced, thereby significantly increasing the effective working life of the cutting mechanism.